Can't open UFO: ValueError Invalid value ('1') for attribute postscriptBlueFuzz.

Can anybody help me understand what the problem is here?
Thanks in advance!

the UFO has a string (text) entry for the postscriptBlueFuzz info value. Which is not allowed. This value must be a integer or a float.

This is not good, where did you get the UFO from?

run this inside RoboFont to get it fixed!

enjoy

from fontParts.ui import GetFile

# get the path to the file
path = GetFile()
print("fixing ufo:", path)

# import the ufo reader/writer
from fontTools.ufoLib import UFOReaderWriter

# create a dummy simple info class to store the info

class SimpleInfo(dict):
    
    def __setattr__(self, key, value):
        self[key] = value
    
    def __getattr__(self, key):
        return self.get(key, None)
    
# if we have a path 
if path:
    # read the ufo, but dont validate
    reader = UFOReaderWriter(path, validate=False)
    # create a info object
    info = SimpleInfo()
    # read the info from the ufo
    reader.readInfo(info)
    # change the postscriptBlueFuzz to an integer
    info.postscriptBlueFuzz = int(info.postscriptBlueFuzz)
    # write it back into the ufo
    reader.writeInfo(info)

# DONE!

• open the UFO package in Finder (right click + Show Package Contents)
• open the file fontinfo.plist in a code editor
• look for <key>postscriptBlueFuzz</key>
• in the line below, replace the <string> tag with <integer>:
  <string>1</string>
<integer>1</integer>

this approach can help you understand how the UFO format works. if you need to do it multiple times, use the script :)

cheers!